Godel universes in string theory

We show that homogeneous Godel spacetimes need not contain closed timelike curves in low-energy-effective string theories. We find exact solutions for the Godel metric in string theory for the full O(alpha') action including both dilaton and axion fields. The results are valid for bosonic, heterotic and super-strings. To first order in the inverse string tension alpha', these solutions display a simple relation between the angular velocity of the Godel universe, Omega, and the inverse string tension of the form alpha' = 1/Omega(3) in the absence of the axion field. The generalization of this relationship is also Found when the axion field is present. [S0556-2821(98)07920-X].